1. Field of the Invention
The present invention relates to controlling unloading of a hard disk drive, and more particularly, to a method and an apparatus for controlling an unload standby time of a hard disk drive according to the accumulated number of unloading operations.
2. Description of Related Art
A hard disk drive (HDD) is a recording device used to store information. In general, information is recorded on concentric tracks in a surface of at least one magnetic recording disk. A disk is mounted on a spindle motor to be rotated, and information is accessed by a reading/recording head mounted on an actuator arm rotated by a voice coil motor (VCM). The VCM is excited by current to rotate an actuator and move a recording head. A reading/recording head senses a magnetic change generated from a disk surface to read information recorded on the disk surface. In order to record data on the track, current is supplied to the recording head. The current generates a magnetic field, and the magnetic field magnetizes the disk surface.
The HDD performs recording/reproducing operations of data in response to a command from a host system.
When the duration of the idle state, that is, a state in which the HDD does not perform a specific operation and is on standby state for receiving the command from the host system, exceeds a predetermined amount of time, a method of unloading (or parking) the head so as to reduce power consumption is known.
FIG. 1 is a flowchart illustrating a conventional unloading control method.
After a command is executed, that is, after an operation requested from the host system is completed, the HDD enters an idle state. At this time, a timer for counting duration of the idle state is initiated in operation S102. The timer is provided to check whether a standby time to perform an unloading operation is passed.
In operation S104, it is checked whether any command from the host computer was received.
If received in operation S104, received commands are executed in operation S106. At this time, the timer is terminated.
If not received in operation S104, it is determined whether the standby time for an unloading operation is passed in operation S108.
If it is determined that the standby time is not passed in operation S108, process returns to operation S102.
If it is determined that the standby time is passed in operation S108, the unloading operation is performed in operation S110.
When the head is unloaded, current is not applied to the VCM while the spindle motor is stopped. Thus, power consumption of the hard disk drive can be minimized. Indeed, it is preferable to unload the head when the idle state is continued more than a predetermined time so as to reduce power consumption, but it is not preferable, taking performance of HDD into consideration, because an amount of time is needed to load the head being unloaded when leaving from the idle state and there is a high possibility of scratching the disk with the head during both unloading and loading operations. As the number of uses increases, performance of the HDD, as well as other devices, decreases little by little over time. If the number of loading/unloading operations of an unloading device of a HDD exceeds a designed number, the possibility of the head colliding with the disk increases, thereby data recorded on the disk is damaged in both loading and unloading operations, becomes higher due to abrasion, elastic deterioration, etc. of mechanical parts.
Since a HDD especially adapted to a mobile device suffers frequent loading/unloading operations, the possibility of damaging data increases further as the number of loading/unloading operations increases.
However, in a conventional method of controlling an unload, when duration of the idle state exceeds a predetermined amount of time, an unloading operation is scheduled to perform unconditionally, and thus the possibility of damaging data according to the unloading device with the designed number of loading/unloading operations is not considered at all.